Building equipment control system with automated horizon selection

ABSTRACT

A method includes automatically selecting a prediction horizon used by the predictive model by performing evaluations of model performance at successively narrower ranges of possible prediction horizons until the prediction horizon is determined based on results of the evaluations. The method may also include using the predictive model with the prediction horizon to perform an automated control action, which may include at least one of controlling or monitoring the building equipment.

BACKGROUND

The present disclosure relates generally to building equipment such as heating, ventilation, or cooling (HVAC) equipment, and building management systems for use with such equipment. Building equipment operate to adjust physical conditions of a building such as temperature, humidity, air quality, etc. A building management system (BMS) is, in general, a system of devices configured to control, monitor, and manage equipment in or around a building or building area. A BMS can include, for example, a HVAC system, a security system, a lighting system, a fire alerting system, any other system that is capable of managing building functions or devices, or any combination thereof.

Systems and devices in a BMS often generate temporal or time-series data that can be analyzed to determine the performance of the BMS and the various components thereof and/or predict future events such as faults, errors, malfunctions, etc. of the building equipment. For example, data can be examined and alert a user to repair the fault before it becomes more severe when the monitored system or process begins to degrade in performance, or to provide other advantageous technical benefits. However, many fault detection or prediction approaches are dependent on pre-existence of a robust set of historical data with multiple instances of different types of fault events. Such robust data is often not available in practice.

SUMMARY

One implementation of the present disclosure is a method for building equipment. The method includes automatically selecting a prediction horizon used by a predictive model for the building equipment by performing evaluations of model performance at successively narrower ranges of possible prediction horizons until the prediction horizon is determined based on results of the evaluations. The method may also include using the predictive model with the prediction horizon to perform an automated control action, which may include at least one of controlling or monitoring the building equipment.

In some embodiments, using the predictive model includes performing fault predictions. The method also may include automatically affecting an operation of the building equipment based on whether a fault of the building equipment is predicted to occur within the prediction horizon using the predictive model.

The method also may include choosing the successively narrower ranges by choosing higher ranges in response to successful results of the evaluations and choosing lower ranges in response to unsuccessful results of the evaluations. The method also may include choosing the successively narrower ranges by dividing an initial range at a midpoint of the initial range, choosing a first narrower range of the successively narrower ranges as a portion of the initial range greater than the midpoint in response to a successful evaluation result based on the midpoint of the initial range, and choosing the first narrower range of the successively narrower ranges as a portion of the initial range less than the midpoint in response to an unsuccessful evaluation result based on the midpoint of the initial range.

The method may include dividing the first narrower range at the midpoint of the first narrower range, choosing a second narrower range of the successively narrower ranges as a portion of the first narrower range greater than the midpoint in response to a successful evaluation result based on the midpoint of the first narrower range, and choosing the second narrower range of the successively narrower ranges as a portion of the first narrower range less than the midpoint in response to an unsuccessful evaluation result based on the midpoint of the first narrower range.

The method may include dividing the second narrower range at the midpoint of the second narrower range, choosing a first end point greater than the midpoint in response to a successful evaluation result based on the midpoint of the first narrower range, and choosing a second end point less than the midpoint in response to an unsuccessful evaluation result based on the midpoint of the first narrower range. In some embodiments, the method includes using the first end point or the second end point as the prediction horizon in response to a successful evaluation result using the first end point or the second end point as the prediction horizon.

In some embodiments, the evaluations include comparing a plurality of performance metrics to a plurality of thresholds. The plurality of performance metrics can include two or more of a precision metric, a recall metric, a false positive rate, a true positive rate, an accuracy metric, and an area under a receiver operating characteristic curve.

In some embodiments, performing the evaluations of model performance at the midpoints includes using the midpoints as the prediction horizons for fault prediction models, training the fault prediction models, and executing tests of the fault prediction models.

Another implementation of the present disclosure is a system providing a predictive model for building equipment. The system may include building equipment and circuitry. The circuitry is programmed to automatically select a prediction horizon for the predictive model by performing evaluations of model performance at successively narrower ranges of possible prediction horizons until the prediction horizon is determined based on results of the evaluations and using the predictive model with the prediction horizon to perform an automated control action, which may include at least one of controlling or monitoring the building equipment.

In some embodiments, the circuitry includes a first portion locally integrated with the building equipment and a second portion at a cloud system, the second portion automatically selects the prediction horizon, trains a machine learning model based on the prediction horizon, modifies the machine learning model to create a modified machine learning model suitable for edge execution, and provides the modified machine learning model to the first portion, and the first portion uses the modified machine learning model to predict whether the fault of the building equipment will occur over the prediction horizon.

In some embodiments, using the predictive model includes performing fault predictions for the building equipment. The circuitry may be programmed to perform the automated control action by automatically influencing operation of the building equipment based on whether a fault is predicted to occur at the prediction horizon.

In some embodiments, the circuitry is also programmed to choose the successively narrower ranges by choosing higher ranges in response to successful results of the evaluations and choosing lower ranges in response to unsuccessful results of the evaluations.

In some embodiments, the circuitry is also programmed to choose the successively narrower ranges by dividing an initial range at a midpoint of the initial range, choosing a first narrower range of the successively narrower ranges as a portion of the initial range greater than the midpoint in response to a successful evaluation result based on the midpoint of the initial range, choosing the first narrower range of the successively narrower ranges as a portion of the initial range less than the midpoint in response to an unsuccessful evaluation result based on the midpoint of the initial range, dividing the first narrower range at the midpoint of the first narrower range, choosing a second narrower range of the successively narrower ranges as a portion of the first narrower range greater than the midpoint in response to a successful evaluation result based on the midpoint of the first narrower range, choosing the second narrower range of the successively narrower ranges as a portion of the first narrower range less than the midpoint in response to an unsuccessful evaluation result based on the midpoint of the first narrower range, dividing the second narrower range at the midpoint of the second narrower range, choosing a first end point greater than the midpoint in response to a successful evaluation result based on the midpoint of the first narrower range, choosing a second end point less than the midpoint in response to an unsuccessful evaluation result based on the midpoint of the first narrower range, and using the first end point or the second end point as the prediction horizon in response to a successful evaluation result using the first end point or the second end point as the prediction horizon.

In some embodiments, the evaluations include comparisons of a plurality of performance metrics to a plurality of thresholds. In some embodiments, the plurality of performance metrics include two or more of a precision metric, a recall metric, a false positive rate, a true positive rate, and accuracy metric, and an area under a receiver operating characteristic curve.

Another implementation of the present disclosure is one or more non-transitory computer-readable media storing instructions that, when executed by one or more processors, perform operations. The operations may include automatically selecting a prediction horizon by performing evaluations of model performance for successively narrower ranges of possible prediction horizons until the prediction horizon is determined based on results of the evaluations, and using the predictive model with the prediction horizon to perform an automated control action for building equipment.

In some embodiments, the operations also include choosing the successively narrower ranges by choosing higher values in response to successful results of the evaluations and choosing lower values in response to unsuccessful results of the evaluations. In some embodiments, the evaluations include comparisons of a plurality of performance metrics to a plurality of thresholds. The plurality of performance metrics can include two or more of a precision metric, a recall metric, a false positive rate, a true positive rate, and accuracy metric, and an area under a receiver operating characteristic curve.

Other aspects, inventive features, and advantages of the devices and/or processes described herein, as defined solely by the claims, will become apparent in the detailed description set forth herein and taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing of a building equipped with a HVAC system, according to some embodiments.

FIG. 2 is a schematic diagram of a waterside system which can be used in conjunction with the building of FIG. 1 , according to some embodiments.

FIG. 3 is a schematic diagram of an airside system which can be used in conjunction with the building of FIG. 1 , according to some embodiments.

FIG. 4 is a block diagram of a building management system (BMS) which can be used to monitor and control the building of FIG. 1 , according to some embodiments.

FIG. 5 is a block diagram of another BMS which can be used to monitor and control the building of FIG. 1 and includes a fault management system, according to some embodiments.

FIG. 6 is a block diagram of another BMS including the fault management system, according to some embodiments.

FIG. 7 is a block diagram of another BMS including the fault management system, according to some embodiments.

FIG. 8 is a block diagram of a system including a detailed view of the fault management system, according to some embodiments.

FIG. 9 is a flowchart of a process for selecting a prediction horizon for a fault prediction model, according to some embodiments.

FIG. 10 is a branch diagram showing example selections that can be made in the process of FIG. 9 , according to some embodiments.

FIG. 11 is an illustration of prediction horizon selection in a first scenario, according to some embodiments.

FIG. 12 is an illustration of prediction horizon selection in a second scenario, according to some embodiments.

FIG. 13 is an illustration of prediction horizon selection in a third scenario, according to some embodiments.

FIG. 14 is a diagram of a process for generating performance metrics in a model evaluation based on a selected horizon point to be evaluated, according to some embodiments.

FIG. 15 is a diagram of a process that includes calculating performance metrics, according to some embodiments.

FIG. 16 is a flowchart of a process for multi-tiered prediction horizon determination, according to some embodiments.

DETAILED DESCRIPTION

Following below are more detailed descriptions of various concepts related to, and implementations of systems, methods, and apparatuses for generating time varying performance indications for connected equipment in a building management system. Before turning to the more detailed descriptions and figures, which illustrate the exemplary embodiments in detail, it should be understood that the application is not limited to the details or methodology set forth in the descriptions or illustrated in the figures. It should also be understood that the terminology is for the purpose of description only and should not be regarded as limiting in any way.

Building HVAC Systems and Building Management Systems

Referring now to FIGS. 1-5 , several building management systems (BMS) and HVAC systems in which the systems and methods of the present disclosure can be implemented are shown, according to some embodiments. In brief overview, FIG. 1 shows a building 10 equipped with a HVAC system 100. FIG. 2 is a block diagram of a waterside system 200 which can be used to serve building 10. FIG. 3 is a block diagram of an airside system 300 which can be used to serve building 10. FIG. 4 is a block diagram of a BMS which can be used to monitor and control building 10. FIG. 5 is a block diagram of another BMS which can be used to monitor and control building 10.

Building 10 and HVAC System 100

Referring particularly to FIG. 1 , a perspective view of building 10 is shown. Building 10 is served by a BMS. A BMS is, in general, a system of devices configured to control, monitor, and manage equipment in or around a building or building area. A BMS can include, for example, a HVAC system, a security system, a lighting system, a fire alerting system, any other system that is capable of managing building functions or devices, or any combination thereof.

The BMS that serves building 10 includes an HVAC system 100. HVAC system 100 can include a plurality of HVAC devices (e.g., heaters, chillers, air handling units, pumps, fans, thermal energy storage, etc.) configured to provide heating, cooling, ventilation, or other services for building 10. For example, HVAC system 100 is shown to include a waterside system 120 and an airside system 130. Waterside system 120 may provide a heated or chilled fluid to an air handling unit of airside system 130. Airside system 130 may use the heated or chilled fluid to heat or cool an airflow provided to building 10. An exemplary waterside system and airside system which can be used in HVAC system 100 are described in greater detail with reference to FIGS. 2 and 3 .

HVAC system 100 is shown to include a chiller 102, a boiler 104, and a rooftop air handling unit (AHU) 106. Waterside system 120 may use boiler 104 and chiller 102 to heat or cool a working fluid (e.g., water, glycol, etc.) and may circulate the working fluid to AHU 106. In various embodiments, the HVAC devices of waterside system 120 can be located in or around building 10 (as shown in FIG. 1 ) or at an offsite location such as a central plant (e.g., a chiller plant, a steam plant, a heat plant, etc.). The working fluid can be heated in boiler 104 or cooled in chiller 102, depending on whether heating or cooling is required in building 10. Boiler 104 may add heat to the circulated fluid, for example, by burning a combustible material (e.g., natural gas) or using an electric heating element. Chiller 102 may place the circulated fluid in a heat exchange relationship with another fluid (e.g., a refrigerant) in a heat exchanger (e.g., an evaporator) to absorb heat from the circulated fluid. The working fluid from chiller 102 and/or boiler 104 can be transported to AHU 106 via piping 108.

AHU 106 may place the working fluid in a heat exchange relationship with an airflow passing through AHU 106 (e.g., via one or more stages of cooling coils and/or heating coils). The airflow can be, for example, outside air, return air from within building 10, or a combination of both. AHU 106 may transfer heat between the airflow and the working fluid to provide heating or cooling for the airflow. For example, AHU 106 can include one or more fans or blowers configured to pass the airflow over or through a heat exchanger containing the working fluid. The working fluid may then return to chiller 102 or boiler 104 via piping 110.

Airside system 130 may deliver the airflow supplied by AHU 106 (i.e., the supply airflow) to building 10 via air supply ducts 112 and may provide return air from building 10 to AHU 106 via air return ducts 114. In some embodiments, airside system 130 includes multiple variable air volume (VAV) units 116. For example, airside system 130 is shown to include a separate VAV unit 116 on each floor or zone of building 10. VAV units 116 can include dampers or other flow control elements that can be operated to control an amount of the supply airflow provided to individual zones of building 10. In other embodiments, airside system 130 delivers the supply airflow into one or more zones of building 10 (e.g., via supply ducts 112) without using intermediate VAV units 116 or other flow control elements. AHU 106 can include various sensors (e.g., temperature sensors, pressure sensors, etc.) configured to measure attributes of the supply airflow. AHU 106 may receive input from sensors located within AHU 106 and/or within the building zone and may adjust the flow rate, temperature, or other attributes of the supply airflow through AHU 106 to achieve setpoint conditions for the building zone.

Waterside System 200

Referring now to FIG. 2 , a block diagram of a waterside system 200 is shown, according to some embodiments. In various embodiments, waterside system 200 may supplement or replace waterside system 120 in HVAC system 100 or can be implemented separate from HVAC system 100. When implemented in HVAC system 100, waterside system 200 can include a subset of the HVAC devices in HVAC system 100 (e.g., boiler 104, chiller 102, pumps, valves, etc.) and may operate to supply a heated or chilled fluid to AHU 106. The HVAC devices of waterside system 200 can be located within building 10 (e.g., as components of waterside system 120) or at an offsite location such as a central plant.

In FIG. 2 , waterside system 200 is shown as a central plant having a plurality of subplants 202-212. Subplants 202-212 are shown to include a heater subplant 202, a heat recovery chiller subplant 204, a chiller subplant 206, a cooling tower subplant 208, a hot thermal energy storage (TES) subplant 210, and a cold thermal energy storage (TES) subplant 212. Subplants 202-212 consume resources (e.g., water, natural gas, electricity, etc.) from utilities to serve thermal energy loads (e.g., hot water, cold water, heating, cooling, etc.) of a building or campus. For example, heater subplant 202 can be configured to heat water in a hot water loop 214 that circulates the hot water between heater subplant 202 and building 10. Chiller subplant 206 can be configured to chill water in a cold water loop 216 that circulates the cold water between chiller subplant 206 building 10. Heat recovery chiller subplant 204 can be configured to transfer heat from cold water loop 216 to hot water loop 214 to provide additional heating for the hot water and additional cooling for the cold water. Condenser water loop 218 may absorb heat from the cold water in chiller subplant 206 and reject the absorbed heat in cooling tower subplant 208 or transfer the absorbed heat to hot water loop 214. Hot TES subplant 210 and cold TES subplant 212 may store hot and cold thermal energy, respectively, for subsequent use.

Hot water loop 214 and cold water loop 216 may deliver the heated and/or chilled water to air handlers located on the rooftop of building 10 (e.g., AHU 106) or to individual floors or zones of building 10 (e.g., VAV units 116). The air handlers push air past heat exchangers (e.g., heating coils or cooling coils) through which the water flows to provide heating or cooling for the air. The heated or cooled air can be delivered to individual zones of building 10 to serve thermal energy loads of building 10. The water then returns to subplants 202-212 to receive further heating or cooling.

Although subplants 202-212 are shown and described as heating and cooling water for circulation to a building, it is understood that any other type of working fluid (e.g., glycol, CO2, etc.) can be used in place of or in addition to water to serve thermal energy loads. In other embodiments, subplants 202-212 may provide heating and/or cooling directly to the building or campus without requiring an intermediate heat transfer fluid. These and other variations to waterside system 200 are within the teachings of the present invention.

Each of subplants 202-212 can include a variety of equipment configured to facilitate the functions of the subplant. For example, heater subplant 202 is shown to include a plurality of heating elements 220 (e.g., boilers, electric heaters, etc.) configured to add heat to the hot water in hot water loop 214. Heater subplant 202 is also shown to include several pumps 222 and 224 configured to circulate the hot water in hot water loop 214 and to control the flow rate of the hot water through individual heating elements 220. Chiller subplant 206 is shown to include a plurality of chillers 232 configured to remove heat from the cold water in cold water loop 216. Chiller subplant 206 is also shown to include several pumps 234 and 236 configured to circulate the cold water in cold water loop 216 and to control the flow rate of the cold water through individual chillers 232.

Heat recovery chiller subplant 204 is shown to include a plurality of heat recovery heat exchangers 226 (e.g., refrigeration circuits) configured to transfer heat from cold water loop 216 to hot water loop 214. Heat recovery chiller subplant 204 is also shown to include several pumps 228 and 230 configured to circulate the hot water and/or cold water through heat recovery heat exchangers 226 and to control the flow rate of the water through individual heat recovery heat exchangers 226. Cooling tower subplant 208 is shown to include a plurality of cooling towers 238 configured to remove heat from the condenser water in condenser water loop 218. Cooling tower subplant 208 is also shown to include several pumps 240 configured to circulate the condenser water in condenser water loop 218 and to control the flow rate of the condenser water through individual cooling towers 238.

Hot TES subplant 210 is shown to include a hot TES tank 242 configured to store the hot water for later use. Hot TES subplant 210 may also include one or more pumps or valves configured to control the flow rate of the hot water into or out of hot TES tank 242. Cold TES subplant 212 is shown to include cold TES tanks 244 configured to store the cold water for later use. Cold TES subplant 212 may also include one or more pumps or valves configured to control the flow rate of the cold water into or out of cold TES tanks 244.

In some embodiments, one or more of the pumps in waterside system 200 (e.g., pumps 222, 224, 228, 230, 234, 236, and/or 240) or pipelines in waterside system 200 include an isolation valve associated therewith. Isolation valves can be integrated with the pumps or positioned upstream or downstream of the pumps to control the fluid flows in waterside system 200. In various embodiments, waterside system 200 can include more, fewer, or different types of devices and/or subplants based on the particular configuration of waterside system 200 and the types of loads served by waterside system 200.

Airside System 300

Referring now to FIG. 3 , a block diagram of an airside system 300 is shown, according to some embodiments. In various embodiments, airside system 300 may supplement or replace airside system 130 in HVAC system 100 or can be implemented separate from HVAC system 100. When implemented in HVAC system 100, airside system 300 can include a subset of the HVAC devices in HVAC system 100 (e.g., AHU 106, VAV units 116, ducts 112-114, fans, dampers, etc.) and can be located in or around building 10. Airside system 300 may operate to heat or cool an airflow provided to building 10 using a heated or chilled fluid provided by waterside system 200.

In FIG. 3 , airside system 300 is shown to include an economizer-type air handling unit (AHU) 302. Economizer-type AHUs vary the amount of outside air and return air used by the air handling unit for heating or cooling. For example, AHU 302 may receive return air 304 from building zone 306 via return air duct 308 and may deliver supply air 310 to building zone 306 via supply air duct 312. In some embodiments, AHU 302 is a rooftop unit located on the roof of building 10 (e.g., AHU 106 as shown in FIG. 1 ) or otherwise positioned to receive both return air 304 and outside air 314. AHU 302 can be configured to operate exhaust air damper 316, mixing damper 318, and outside air damper 320 to control an amount of outside air 314 and return air 304 that combine to form supply air 310. Any return air 304 that does not pass through mixing damper 318 can be exhausted from AHU 302 through exhaust damper 316 as exhaust air 322.

Each of dampers 316-320 can be operated by an actuator. For example, exhaust air damper 316 can be operated by actuator 324, mixing damper 318 can be operated by actuator 326, and outside air damper 320 can be operated by actuator 328. Actuators 324-328 may communicate with an AHU controller 330 via a communications link 332. Actuators 324-328 may receive control signals from AHU controller 330 and may provide feedback signals to AHU controller 330. Feedback signals can include, for example, an indication of a current actuator or damper position, an amount of torque or force exerted by the actuator, diagnostic information (e.g., results of diagnostic tests performed by actuators 324-328), status information, commissioning information, configuration settings, calibration data, and/or other types of information or data that can be collected, stored, or used by actuators 324-328. AHU controller 330 can be an economizer controller configured to use one or more control algorithms (e.g., state-based algorithms, extremum seeking control (ESC) algorithms, proportional-integral (PI) control algorithms, proportional-integral-derivative (PID) control algorithms, model predictive control (MPC) algorithms, feedback control algorithms, etc.) to control actuators 324-328.

Still referring to FIG. 3 , AHU 302 is shown to include a cooling coil 334, a heating coil 336, and a fan 338 positioned within supply air duct 312. Fan 338 can be configured to force supply air 310 through cooling coil 334 and/or heating coil 336 and provide supply air 310 to building zone 306. AHU controller 330 may communicate with fan 338 via communications link 340 to control a flow rate of supply air 310. In some embodiments, AHU controller 330 controls an amount of heating or cooling applied to supply air 310 by modulating a speed of fan 338.

Cooling coil 334 may receive a chilled fluid from waterside system 200 (e.g., from cold water loop 216) via piping 342 and may return the chilled fluid to waterside system 200 via piping 344. Valve 346 can be positioned along piping 342 or piping 344 to control a flow rate of the chilled fluid through cooling coil 334. In some embodiments, cooling coil 334 includes multiple stages of cooling coils that can be independently activated and deactivated (e.g., by AHU controller 330, by BMS controller 366, etc.) to modulate an amount of cooling applied to supply air 310.

Heating coil 336 may receive a heated fluid from waterside system 200 (e.g., from hot water loop 214) via piping 348 and may return the heated fluid to waterside system 200 via piping 350. Valve 352 can be positioned along piping 348 or piping 350 to control a flow rate of the heated fluid through heating coil 336. In some embodiments, heating coil 336 includes multiple stages of heating coils that can be independently activated and deactivated (e.g., by AHU controller 330, by BMS controller 366, etc.) to modulate an amount of heating applied to supply air 310.

Each of valves 346 and 352 can be controlled by an actuator. For example, valve 346 can be controlled by actuator 354 and valve 352 can be controlled by actuator 356. Actuators 354-356 may communicate with AHU controller 330 via communications links 358-360. Actuators 354-356 may receive control signals from AHU controller 330 and may provide feedback signals to controller 330. In some embodiments, AHU controller 330 receives a measurement of the supply air temperature from a temperature sensor 362 positioned in supply air duct 312 (e.g., downstream of cooling coil 334 and/or heating coil 336). AHU controller 330 may also receive a measurement of the temperature of building zone 306 from a temperature sensor 364 located in building zone 306.

In some embodiments, AHU controller 330 operates valves 346 and 352 via actuators 354-356 to modulate an amount of heating or cooling provided to supply air 310 (e.g., to achieve a setpoint temperature for supply air 310 or to maintain the temperature of supply air 310 within a setpoint temperature range). The positions of valves 346 and 352 affect the amount of heating or cooling provided to supply air 310 by cooling coil 334 or heating coil 336 and may correlate with the amount of energy consumed to achieve a desired supply air temperature. AHU 330 may control the temperature of supply air 310 and/or building zone 306 by activating or deactivating coils 334-336, adjusting a speed of fan 338, or a combination of both.

Still referring to FIG. 3 , airside system 300 is shown to include a building management system (BMS) controller 366 and a client device 368. BMS controller 366 can include one or more computer systems (e.g., servers, supervisory controllers, subsystem controllers, etc.) that serve as system level controllers, application or data servers, head nodes, or master controllers for airside system 300, waterside system 200, HVAC system 100, and/or other controllable systems that serve building 10. BMS controller 366 may communicate with multiple downstream building systems or subsystems (e.g., HVAC system 100, a security system, a lighting system, waterside system 200, etc.) via a communications link 370 according to like or disparate protocols (e.g., LON, BACnet, etc.). In various embodiments, AHU controller 330 and BMS controller 366 can be separate (as shown in FIG. 3 ) or integrated. In an integrated implementation, AHU controller 330 can be a software module configured for execution by a processor of BMS controller 366.

In some embodiments, AHU controller 330 receives information from BMS controller 366 (e.g., commands, setpoints, operating boundaries, etc.) and provides information to BMS controller 366 (e.g., temperature measurements, valve or actuator positions, operating statuses, diagnostics, etc.). For example, AHU controller 330 may provide BMS controller 366 with temperature measurements from temperature sensors 362-364, equipment on/off states, equipment operating capacities, and/or any other information that can be used by BMS controller 366 to monitor or control a variable state or condition within building zone 306.

Client device 368 can include one or more human-machine interfaces or client interfaces (e.g., graphical user interfaces, reporting interfaces, text-based computer interfaces, client-facing web services, web servers that provide pages to web clients, etc.) for controlling, viewing, or otherwise interacting with HVAC system 100, its subsystems, and/or devices. Client device 368 can be a computer workstation, a client terminal, a remote or local interface, or any other type of user interface device. Client device 368 can be a stationary terminal or a mobile device. For example, client device 368 can be a desktop computer, a computer server with a user interface, a laptop computer, a tablet, a smartphone, a PDA, or any other type of mobile or non-mobile device. Client device 368 may communicate with BMS controller 366 and/or AHU controller 330 via communications link 372.

Building Management System 400

Referring now to FIG. 4 , a block diagram of a building management system (BMS) 400 is shown, according to some embodiments. BMS 400 can be implemented in building 10 to automatically monitor and control various building functions. BMS 400 is shown to include BMS controller 366 and a plurality of building subsystems 428. Building subsystems 428 are shown to include a building electrical subsystem 434, an information communication technology (ICT) subsystem 436, a security subsystem 438, a HVAC subsystem 440, a lighting subsystem 442, a lift/escalators subsystem 432, and a fire safety subsystem 430. In various embodiments, building subsystems 428 can include fewer, additional, or alternative subsystems. For example, building subsystems 428 may also or alternatively include a refrigeration subsystem, an advertising or signage subsystem, a cooking subsystem, a vending subsystem, a printer or copy service subsystem, or any other type of building subsystem that uses controllable equipment and/or sensors to monitor or control building 10. In some embodiments, building subsystems 428 include waterside system 200 and/or airside system 300, as described with reference to FIGS. 2 and 3 .

Each of building subsystems 428 can include any number of devices, controllers, and connections for completing its individual functions and control activities. HVAC subsystem 440 can include many of the same components as HVAC system 100, as described with reference to FIGS. 1-3 . For example, HVAC subsystem 440 can include a chiller, a boiler, any number of air handling units, economizers, field controllers, supervisory controllers, actuators, temperature sensors, thermostats, and other devices for controlling the temperature, humidity, airflow, or other variable conditions within building 10. Lighting subsystem 442 can include any number of light fixtures, ballasts, lighting sensors, dimmers, and/or other devices configured to controllably adjust the amount of light provided to a building space. Security subsystem 438 can include occupancy sensors, video surveillance cameras, digital video recorders, video processing servers, intrusion detection devices, access control devices and servers, and/or other security-related devices.

Still referring to FIG. 4 , BMS controller 366 is shown to include a communications interface 407 and a BMS interface 409. Communications interface 407 may facilitate communications between BMS controller 366 and external applications (e.g., monitoring and reporting applications 422, enterprise control applications 426, remote systems and applications 444, applications residing on client devices 448, etc.) for allowing user control, monitoring, and adjustment to BMS controller 366 and/or subsystems 428. Communications interface 407 may also facilitate communications between BMS controller 366 and client devices 448. BMS interface 409 may facilitate communications between BMS controller 366 and building subsystems 428 (e.g., HVAC, lighting security, lifts, power distribution, business, etc.).

Communications interfaces 407 and/or BMS interface 409 can be or include wired or wireless communications interfaces (e.g., jacks, antennas, transmitters, receivers, transceivers, wire terminals, etc.) for conducting data communications with building subsystems 428 or other external systems or devices. In various embodiments, communications via communications interfaces 407 and/or BMS interface 409 can be direct (e.g., local wired or wireless communications) or via a communications network 446 (e.g., a WAN, the Internet, a cellular network, etc.). For example, communications interfaces 407 and/or BMS interface 409 can include an Ethernet card and port for sending and receiving data via an Ethernet-based communications link or network. In another example, communications interfaces 407 and/or BMS interface 409 can include a Wi-Fi transceiver for communicating via a wireless communications network. In another example, one or both of communications interfaces 407 and BMS interface 409 can include cellular or mobile phone communications transceivers. In one embodiment, communications interface 407 is a power line communications interface and BMS interface 409 is an Ethernet interface. In other embodiments, both communications interface 407 and BMS interface 409 are Ethernet interfaces or are the same Ethernet interface.

Still referring to FIG. 4 , BMS controller 366 is shown to include a processing circuit 404 including a processor 406 and memory 408. Processing circuit 404 can be communicably connected to BMS interface 409 and/or communications interface 407 such that processing circuit 404 and the various components thereof can send and receive data via communications interfaces 407 and/or BMS interface 409. Processor 406 can be implemented as a general purpose processor, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a group of processing components, or other suitable electronic processing components.

Memory 408 (e.g., memory, memory unit, storage device, etc.) can include one or more devices (e.g., RAM, ROM, Flash memory, hard disk storage, etc.) for storing data and/or computer code for completing or facilitating the various processes, layers and modules described in the present application. Memory 408 can be or include volatile memory or non-volatile memory. Memory 408 can include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described in the present application. According to some embodiments, memory 408 is communicably connected to processor 406 via processing circuit 404 and includes computer code for executing (e.g., by processing circuit 404 and/or processor 406) one or more processes described herein.

In some embodiments, BMS controller 366 is implemented within a single computer (e.g., one server, one housing, etc.). In various other embodiments BMS controller 366 can be distributed across multiple servers or computers (e.g., that can exist in distributed locations). Further, while FIG. 4 shows applications 422 and 426 as existing outside of BMS controller 366, in some embodiments, applications 422 and 426 can be hosted within BMS controller 366 (e.g., within memory 408).

Still referring to FIG. 4 , memory 408 is shown to include an enterprise integration layer 410, an automated measurement and validation (AM&V) layer 412, a demand response (DR) layer 414, a fault detection and diagnostics (FDD) layer 416, an integrated control layer 418, and a building subsystem integration later 420. Layers 410-420 can be configured to receive inputs from building subsystems 428 and other data sources, determine optimal control actions for building subsystems 428 based on the inputs, generate control signals based on the optimal control actions, and provide the generated control signals to building subsystems 428. The following paragraphs describe some of the general functions performed by each of layers 410-420 in BMS 400.

Enterprise integration layer 410 can be configured to serve clients or local applications with information and services to support a variety of enterprise-level applications. For example, enterprise control applications 426 can be configured to provide subsystem-spanning control to a graphical user interface (GUI) or to any number of enterprise-level business applications (e.g., accounting systems, user identification systems, etc.). Enterprise control applications 426 may also or alternatively be configured to provide configuration GUIs for configuring BMS controller 366. In yet other embodiments, enterprise control applications 426 can work with layers 410-420 to optimize building performance (e.g., efficiency, energy use, comfort, or safety) based on inputs received at communications interface 407 and/or BMS interface 409.

Building subsystem integration layer 420 can be configured to manage communications between BMS controller 366 and building subsystems 428. For example, building subsystem integration layer 420 may receive sensor data and input signals from building subsystems 428 and provide output data and control signals to building subsystems 428. Building subsystem integration layer 420 may also be configured to manage communications between building subsystems 428. Building subsystem integration layer 420 translate communications (e.g., sensor data, input signals, output signals, etc.) across a plurality of multi-vendor/multi-protocol systems.

Demand response layer 414 can be configured to optimize resource usage (e.g., electricity use, natural gas use, water use, etc.) and/or the monetary cost of such resource usage in response to satisfy the demand of building 10. The optimization can be based on time-of-use prices, curtailment signals, energy availability, or other data received from utility providers, distributed energy generation systems 424, from energy storage 427 (e.g., hot TES 242, cold TES 244, etc.), or from other sources. Demand response layer 414 may receive inputs from other layers of BMS controller 366 (e.g., building subsystem integration layer 420, integrated control layer 418, etc.). The inputs received from other layers can include environmental or sensor inputs (e.g., internal to building 10, external to building 10, etc.) such as temperature, carbon dioxide levels, relative humidity levels, air quality sensor outputs, occupancy sensor outputs, room schedules, weather conditions, and the like. The inputs may also include inputs such as electrical use (e.g., expressed in kWh), thermal load measurements, pricing information, projected pricing, smoothed pricing, curtailment signals from utilities, and the like.

According to some embodiments, demand response layer 414 includes control logic for responding to the data and signals it receives. These responses can include communicating with the control algorithms in integrated control layer 418, changing control strategies, changing setpoints, or activating/deactivating building equipment or subsystems in a controlled manner. Demand response layer 414 may also include control logic configured to determine when to utilize stored energy. For example, demand response layer 414 may determine to begin using energy from energy storage 427 just prior to the beginning of a peak use hour.

In some embodiments, demand response layer 414 includes a control module configured to actively initiate control actions (e.g., automatically changing setpoints, etc.) which minimize energy costs based on one or more inputs representative of or based on demand (e.g., price, a curtailment signal, a demand level, etc.). In some embodiments, demand response layer 414 uses equipment models to determine an optimal set of control actions. The equipment models can include, for example, thermodynamic models describing the inputs, outputs, and/or functions performed by various sets of building equipment. Equipment models may represent collections of building equipment (e.g., subplants, chiller arrays, etc.) or individual devices (e.g., individual chillers, heaters, pumps, etc.).

Demand response layer 414 may further include or draw upon one or more demand response policy definitions (e.g., databases, XML, files, etc.). The policy definitions can be edited or adjusted by a user (e.g., via a graphical user interface, etc.) so that the control actions initiated in response to demand inputs can be tailored for the user's application, desired comfort level, particular building equipment, and/or based on other concerns. For example, the demand response policy definitions can specify which equipment can be turned on or off in response to particular demand inputs, how long a system or piece of equipment should be turned off, what setpoints can be changed, what the allowable set point adjustment range is, how long to hold a high demand setpoint before returning to a normally scheduled setpoint, how close to approach capacity limits, which equipment modes to utilize, the energy transfer rates (e.g., the maximum rate, an alarm rate, other rate boundary information, etc.) into and out of energy storage devices (e.g., thermal storage tanks, battery banks, etc.), and/or when to dispatch on-site generation of energy (e.g., via fuel cells, a motor generator set, etc.).

Integrated control layer 418 can be configured to use the data input or output of building subsystem integration layer 420 and/or demand response later 414 to make control decisions. Due to the subsystem integration provided by building subsystem integration layer 420, integrated control layer 418 can integrate control activities of the subsystems 428 such that the subsystems 428 behave as a single integrated supersystem. In some embodiments, integrated control layer 418 includes control logic that uses inputs and outputs from a plurality of building subsystems to provide greater comfort and energy savings relative to the comfort and energy savings that separate subsystems could provide alone. For example, integrated control layer 418 can be configured to use an input from a first subsystem to make an energy-saving control decision for a second subsystem. Results of these decisions can be communicated back to building subsystem integration layer 420.

Integrated control layer 418 is shown to be logically below demand response layer 414. Integrated control layer 418 can be configured to enhance the effectiveness of demand response layer 414 by enabling building subsystems 428 and their respective control loops to be controlled in coordination with demand response layer 414. This configuration may advantageously reduce disruptive demand response behavior relative to conventional systems. For example, integrated control layer 418 can be configured to assure that a demand response-driven upward adjustment to the setpoint for chilled water temperature (or another component that directly or indirectly affects temperature) does not result in an increase in fan energy (or other energy used to cool a space) that would result in greater total building energy use than was saved at the chiller.

Integrated control layer 418 can be configured to provide feedback to demand response layer 414 so that demand response layer 414 checks that constraints (e.g., temperature, lighting levels, etc.) are properly maintained even while demanded load shedding is in progress. The constraints may also include setpoint or sensed boundaries relating to safety, equipment operating limits and performance, comfort, fire codes, electrical codes, energy codes, and the like. Integrated control layer 418 is also logically below fault detection and diagnostics layer 416 and automated measurement and validation layer 412. Integrated control layer 418 can be configured to provide calculated inputs (e.g., aggregations) to these higher levels based on outputs from more than one building subsystem.

Automated measurement and validation (AM&V) layer 412 can be configured to verify that control strategies commanded by integrated control layer 418 or demand response layer 414 are working properly (e.g., using data aggregated by AM&V layer 412, integrated control layer 418, building subsystem integration layer 420, FDD layer 416, or otherwise). The calculations made by AM&V layer 412 can be based on building system energy models and/or equipment models for individual BMS devices or subsystems. For example, AM&V layer 412 may compare a model-predicted output with an actual output from building subsystems 428 to determine an accuracy of the model.

Fault detection and diagnostics (FDD) layer 416 can be configured to provide on-going fault detection for building subsystems 428, building subsystem devices (i.e., building equipment), and control algorithms used by demand response layer 414 and integrated control layer 418. FDD layer 416 may receive data inputs from integrated control layer 418, directly from one or more building subsystems or devices, and/or from another data source. FDD layer 416 may automatically diagnose and respond to detected faults. The responses to detected or diagnosed faults can include providing an alert message to a user, a maintenance scheduling system, or a control algorithm configured to attempt to repair the fault or to work-around the fault.

FDD layer 416 can be configured to output a specific identification of the faulty component or cause of the fault (e.g., loose damper linkage, etc.) using detailed subsystem inputs available at building subsystem integration layer 420. In other exemplary embodiments, FDD layer 416 is configured to provide “fault” events to integrated control layer 418 which executes control strategies and policies in response to the received fault events. According to some embodiments, FDD layer 416 (or a policy executed by an integrated control engine or business rules engine) may shut-down systems or direct control activities around faulty devices or systems to reduce energy waste, extend equipment life, or assure proper control response.

FDD layer 416 can be configured to store or access a variety of different system data stores (or data points for live data). FDD layer 416 may use some content of the data stores to identify faults at the equipment level (e.g., specific chiller, specific AHU, specific terminal unit, etc.) and other content to identify faults at component or subsystem levels. For example, building subsystems 428 may generate temporal (i.e., time-series) data indicating the performance of BMS 400 and the various components thereof. The data generated by building subsystems 428 can include measured or calculated values that exhibit statistical characteristics and provide information about how the corresponding system or process (e.g., a temperature control process, a flow control process, etc.) is performing in terms of error from its setpoint. These processes can be examined by FDD layer 416 to expose when the system begins to degrade in performance and alert a user to repair the fault before it becomes more severe.

Building Management System 500

Referring now to FIG. 5 , a block diagram of another building management system (BMS) 500 is shown, according to some embodiments. BMS 500 can be used to monitor and control the devices of HVAC system 100, waterside system 200, airside system 300, building subsystems 428, as well as other types of BMS devices (e.g., lighting equipment, security equipment, etc.) and/or HVAC equipment. In some embodiments, the building management system includes a fault management system.

BMS 500 provides a system architecture that facilitates automatic equipment discovery and equipment model distribution. Equipment discovery can occur on multiple levels of BMS 500 across multiple different communications busses (e.g., a system bus 554, zone buses 556-560 and 564, sensor/actuator bus 566, etc.) and across multiple different communications protocols. In some embodiments, equipment discovery is accomplished using active node tables, which provide status information for devices connected to each communications bus. For example, each communications bus can be monitored for new devices by monitoring the corresponding active node table for new nodes. When a new device is detected, BMS 500 can begin interacting with the new device (e.g., sending control signals, using data from the device) without user interaction.

Some devices in BMS 500 present themselves to the network using equipment models. An equipment model defines equipment object attributes, view definitions, schedules, trends, and the associated BACnet value objects (e.g., analog value, binary value, multistate value, etc.) that are used for integration with other systems. Some devices in BMS 500 store their own equipment models. Other devices in BMS 500 have equipment models stored externally (e.g., within other devices). For example, a zone coordinator 508 can store the equipment model for a bypass damper 528. In some embodiments, zone coordinator 508 automatically creates the equipment model for bypass damper 528 or other devices on zone bus 558. Other zone coordinators can also create equipment models for devices connected to their zone busses. The equipment model for a device can be created automatically based on the types of data points exposed by the device on the zone bus, device type, and/or other device attributes. Several examples of automatic equipment discovery and equipment model distribution are discussed in greater detail below.

Still referring to FIG. 5 , BMS 500 is shown to include a fault management system 502; a system manager 503; several zone coordinators 506, 508, 510 and 518; and several zone controllers 524, 530, 532, 536, 548, and 550. System manager 503 can monitor various data points in BMS 500 and report monitored variables to fault management system 502. System manager 503 can communicate with client devices 504 (e.g., user devices, desktop computers, laptop computers, mobile devices, etc.) via a data communications link 574 (e.g., BACnet IP, Ethernet, wired or wireless communications, etc.). System manager 503 can provide a user interface to client devices 504 via data communications link 574. The user interface may allow users to monitor and/or control BMS 500 via client devices 504.

In some embodiments, system manager 503 is connected with zone coordinators 506-510 and 518 via a system bus 554. System manager 503 can be configured to communicate with zone coordinators 506-510 and 518 via system bus 554 using a master-slave token passing (MSTP) protocol or any other communications protocol. System bus 554 can also connect system manager 503 with other devices such as a constant volume (CV) rooftop unit (RTU) 512, an input/output module (IOM) 514, a thermostat controller 516 (e.g., a TEC5000 series thermostat controller), and a network automation engine (NAE) or third-party controller 520. RTU 512 can be configured to communicate directly with system manager 503 and can be connected directly to system bus 554. Other RTUs can communicate with system manager 503 via an intermediate device. For example, a wired input 562 can connect a third-party RTU 542 to thermostat controller 516, which connects to system bus 554.

System manager 503 can provide a user interface for any device containing an equipment model. Devices such as zone coordinators 506-510 and 518 and thermostat controller 516 can provide their equipment models to system manager 503 via system bus 554. In some embodiments, system manager 503 automatically creates equipment models for connected devices that do not contain an equipment model (e.g., IOM 514, third party controller 520, etc.). For example, system manager 503 can create an equipment model for any device that responds to a device tree request. The equipment models created by system manager 503 can be stored within system manager 503. System manager 503 can then provide a user interface for devices that do not contain their own equipment models using the equipment models created by system manager 503. In some embodiments, system manager 503 stores a view definition for each type of equipment connected via system bus 554 and uses the stored view definition to generate a user interface for the equipment.

Each zone coordinator 506-510 and 518 can be connected with one or more of zone controllers 524, 530-532, 536, and 548-550 via zone buses 556, 558, 560, and 564. Zone coordinators 506-510 and 518 can communicate with zone controllers 524, 530-532, 536, and 548-550 via zone busses 556-560 and 564 using a MSTP protocol or any other communications protocol. Zone busses 556-560 and 564 can also connect zone coordinators 506-510 and 518 with other types of devices such as variable air volume (VAV) RTUs 522 and 540, changeover bypass (COBP) RTUs 526 and 552, bypass dampers 528 and 546, and PEAK controllers 534 and 544.

Zone coordinators 506-510 and 518 can be configured to monitor and command various zoning systems. In some embodiments, each zone coordinator 506-510 and 518 monitors and commands a separate zoning system and is connected to the zoning system via a separate zone bus. For example, zone coordinator 506 can be connected to VAV RTU 522 and zone controller 524 via zone bus 556. Zone coordinator 508 can be connected to COBP RTU 526, bypass damper 528, COBP zone controller 530, and VAV zone controller 532 via zone bus 558. Zone coordinator 510 can be connected to PEAK controller 534 and VAV zone controller 536 via zone bus 560. Zone coordinator 518 can be connected to PEAK controller 544, bypass damper 546, COBP zone controller 548, and VAV zone controller 550 via zone bus 564.

A single model of zone coordinator 506-510 and 518 can be configured to handle multiple different types of zoning systems (e.g., a VAV zoning system, a COBP zoning system, etc.). Each zoning system can include a RTU, one or more zone controllers, and/or a bypass damper. For example, zone coordinators 506 and 510 are shown as Verasys VAV engines (VVEs) connected to VAV RTUs 522 and 540, respectively. Zone coordinator 506 is connected directly to VAV RTU 522 via zone bus 556, whereas zone coordinator 510 is connected to a third-party VAV RTU 540 via a wired input 568 provided to PEAK controller 534. Zone coordinators 508 and 518 are shown as Verasys COBP engines (VCEs) connected to COBP RTUs 526 and 552, respectively. Zone coordinator 508 is connected directly to COBP RTU 526 via zone bus 558, whereas zone coordinator 518 is connected to a third-party COBP RTU 552 via a wired input 570 provided to PEAK controller 544.

Zone controllers 524, 530-532, 536, and 548-550 can communicate with individual BMS devices (e.g., sensors, actuators, etc.) via sensor/actuator (SA) busses. For example, VAV zone controller 536 is shown connected to networked sensors 538 via SA bus 566. Zone controller 536 can communicate with networked sensors 538 using a MSTP protocol or any other communications protocol. Although only one SA bus 566 is shown in FIG. 5 , it should be understood that each zone controller 524, 530-532, 536, and 548-550 can be connected to a different SA bus. Each SA bus can connect a zone controller with various sensors (e.g., temperature sensors, humidity sensors, pressure sensors, light sensors, occupancy sensors, etc.), actuators (e.g., damper actuators, valve actuators, etc.) and/or other types of controllable equipment (e.g., chillers, heaters, fans, pumps, etc.).

Each zone controller 524, 530-532, 536, and 548-550 can be configured to monitor and control a different building zone. Zone controllers 524, 530-532, 536, and 548-550 can use the inputs and outputs provided via their SA busses to monitor and control various building zones. For example, a zone controller 536 can use a temperature input received from networked sensors 538 via SA bus 566 (e.g., a measured temperature of a building zone) as feedback in a temperature control algorithm. Zone controllers 524, 530-532, 536, and 548-550 can use various types of control algorithms (e.g., state-based algorithms, extremum seeking control (ESC) algorithms, proportional-integral (PI) control algorithms, proportional-integral-derivative (PID) control algorithms, model predictive control (MPC) algorithms, feedback control algorithms, etc.) to control a variable state or condition (e.g., temperature, humidity, airflow, lighting, etc.) in or around building 10.

Fault Management System for Connected Equipment

Referring now to FIG. 6 , a block diagram of another building management system (BMS) 600 which includes a fault management system for connected equipment is shown, according to some embodiments. BMS 600 can include many of the same components as BMS 400 and BMS 500 as described with reference to FIGS. 4 and 5 . For example, BMS 600 is shown to include building 10, network 446, client devices 448, and fault management system 502. Building 10 is shown to include connected equipment 610, which can include any type of equipment used to monitor and/or control building 10. Connected equipment 610 can include connected chillers 612, connected AHUs 614, connected actuators 616, connected controllers 618, or any other type of equipment in a building HVAC system (e.g., boilers, economizers, valves, dampers, cooling towers, fans, pumps, etc.) or building management system (e.g., lighting equipment, security equipment, refrigeration equipment, etc.). Connected equipment 610 can include any of the equipment of HVAC system 100, waterside system 200, airside system 300, BMS 400, and/or BMS 500, as described with reference to FIGS. 1-5 .

Connected equipment 610 can be outfitted with sensors to monitor particular conditions of the connected equipment 610. For example, chillers 612 can include sensors configured to monitor chiller variables such as chilled water return temperature, chilled water supply temperature, chilled water flow status (e.g., mass flow rate, volume flow rate, etc.), condensing water return temperature, condensing water supply temperature, motor amperage (e.g., of a compressor, etc.), variable speed drive (VSD) output frequency, and refrigerant properties (e.g., refrigerant pressure, refrigerant temperature, condenser pressure, evaporator pressure, etc.) at various locations in the refrigeration circuit. Similarly, AHUs 614 can be outfitted with sensors to monitor AHU variables such as supply air temperature and humidity, outside air temperature and humidity, return air temperature and humidity, chilled fluid temperature, heated fluid temperature, damper position, etc. In general, connected equipment 610 monitor and report variables that characterize the performance of the connected equipment 610. Each monitored variable can be forwarded to network control engine 608 as a data point (e.g., including a point ID, a point value, etc.).

Monitored variables can include any measured or calculated values indicating the performance of connected equipment 610 and/or the components thereof. For example, monitored variables can include one or more measured or calculated temperatures (e.g., refrigerant temperatures, cold water supply temperatures, hot water supply temperatures, supply air temperatures, zone temperatures, etc.), pressures (e.g., evaporator pressure, condenser pressure, supply air pressure, etc.), flow rates (e.g., cold water flow rates, hot water flow rates, refrigerant flow rates, supply air flow rates, etc.), valve positions, resource consumptions (e.g., power consumption, water consumption, electricity consumption, etc.), control setpoints, model parameters (e.g., regression model coefficients, etc.), and/or any other time-series values that provide information about how the corresponding system, device, and/or process is performing. Monitored variables can be received from connected equipment 610 and/or from various components thereof. For example, monitored variables can be received from one or more controllers (e.g., BMS controllers, subsystem controllers, HVAC controllers, subplant controllers, AHU controllers, device controllers, etc.), BMS devices (e.g., chillers, cooling towers, pumps, heating elements, etc.), and/or collections of BMS devices.

Connected equipment 610 can also report equipment status information. Equipment status information can include, for example, the operational status of the equipment, an operating mode (e.g., low load, medium load, high load, etc.), an indication of whether the equipment is running under normal or abnormal conditions, a fault code, and/or any other information that indicates the current status of connected equipment 610. In some embodiments, equipment status information reported by the connected equipment 610 is in the form of status codes. For example, four types of status codes can be reported by a connected equipment (e.g., chiller), including safety shutdown codes (safety codes), warning codes, cycling codes, and operation codes. Monitored variables and status codes can be referred to as real timeseries data, which may encompass virtual points or calculated metrics.

In some embodiments, each device of connected equipment 610 includes a control panel. The control panel can use the sensor data to shut down the device if the control panel determines that the device is operating under unsafe conditions. For example, the control panel can compare the sensor data (or a value derived from the sensor data) to predetermined thresholds. If the sensor data or calculated value crosses a safety threshold, the control panel can shut down the device and/or operate the device at a derated setpoint. The control panel can generate a data point when a safety shut down or a derate occurs. The data point can include a safety fault code which indicates the reason or condition that triggered the shut down or derate.

Connected equipment 610 can provide monitored variables and equipment status information to a network control engine 608. Network control engine 608 can include a building controller (e.g., BMS controller 366), a system manager (e.g., system manager 503), a network automation engine (e.g., NAE 520), or any other system or device of building 10 configured to communicate with connected equipment 610. In some embodiments, the monitored variables and the equipment status information are provided to network control engine 608 as data points. Each data point can include a point ID and/or a point value. The point ID can identify the type of data point and/or a variable measured by the data point (e.g., condenser pressure, refrigerant temperature, fault code, etc.). Monitored variables can be identified by name or by an alphanumeric code (e.g., Chilled_Water_Temp, 7694, etc.). The point value can include an alphanumeric value indicating the current value of the data point (e.g., 44° F., fault code 4, etc.).

Network control engine 608 can broadcast the monitored variables and the equipment status information to a remote operations center (ROC) 602. ROC 602 can provide remote monitoring services and can send an alert to building 10 in the event of a critical alarm. ROC 602 can push the monitored variables and equipment status information to a reporting database 604, where the data is stored for reporting and analysis. Fault management system 502 can access database 604 to retrieve the monitored variables and the equipment status information.

In some embodiments, fault management system 502 is a component of BMS controller 366 (e.g., within FDD layer 416). For example, fault management system 502 can be implemented as part of a METASYS® brand building automation system, as sold by Johnson Controls Inc. In other embodiments, fault management system 502 can be a component of a remote computing system or cloud-based computing system configured to receive and process data from one or more building management systems. For example, fault management system 502 can connect the connected equipment 610 (e.g., chillers 612) to the cloud and collect real-time data for over a number of points (e.g., 50 points) on those equipment. In other embodiments, fault management system 502 can be a component of a subsystem level controller (e.g., a HVAC controller, etc.), a subplant controller, a device controller (e.g., AHU controller 330, a chiller controller, etc.), a field controller, a computer workstation, a client device, and/or any other system and/or device that receives and processes monitored variables from connected equipment 610.

Fault management system 502 may use the monitored variables and status information to predict upcoming faults (e.g., failure modes) of the connected equipment 610 and take action to prevent or mitigate such faults. The fault management system 502 is described in further detail below with reference to FIGS. 8-13 . Communications between fault management system 502 and other systems and/or devices can be direct and/or via an intermediate communications network, such as network 446.

In some embodiments, fault management system 502 provides a web interface which can be accessed by service technicians 606, client devices 448, and other systems or devices. The web interface can be used to access the raw data in reporting database 604, view the results produced by the fault management system, identify which equipment is in need of preventative maintenance, and otherwise interact with fault management system 502. Service technicians 606 can access the web interface to view a list of equipment for which faults are predicted by fault management system 502. Service technicians 606 can use the predicted faults to proactively repair connected equipment 610 before a fault and/or an unexpected shut down occurs. These and other features of fault management system 502 are described in greater detail below.

Referring now to FIG. 7 , a block diagram of another building management system (BMS) 650 is shown, according to some embodiments. The building management system 650 of FIG. 7 includes the components of the building management system 600 of FIG. 6 , plus any number of additional buildings 10 with additional groups of connected equipment 610. The multiple buildings 10 and multiple units of connected 610 can be considered as a fleet of buildings and/or equipment. The buildings 10 and connected equipment 610 can be located in one location (e.g., one campus) or multiple locations, including across geographic regions, states, provinces, territories, countries, continents, etc. FIG. 7 illustrates that the network 446 can connect all such buildings 10 and connected equipment 610 to the remote operations center 602 (e.g., via the Internet). The fault management system 502 can then be provided as a cloud-based service, for example. In other embodiments, the fault management system 502 is implemented at the edge, for example locally on unit of connected equipment 610.

Referring now to FIG. 8 , a block diagram of a system 800 including a detailed view of the fault management system 502 is shown, according to some embodiments. The system 800 includes the fault management system 502, the connected equipment 610 serving the building 10, a connected equipment controller 802 for the connected equipment 610, a building controller 804 for other controllable devices of the building 10, and a work order system 806. The fault management system 502 is shown as including a fault prediction model 808, an equipment operational change model 810, a building operational change model 812, a maintenance model 814, root cause discovery tool 816, and training engine 818. The fault management system 502 can be implemented as one or more processors and one or more non-transitory computer readable media storing program instructions that, when executed by one or more processors, cause the processors to perform the operations attributed herein to the fault management system 502 and components thereof. The fault management system 502 can be implemented as a cloud-based computing resource, at the edge (e.g., embedded in the connected equipment), locally at data infrastructure of the building 10, or various combinations thereof in various embodiments.

The fault prediction model 808 is shown as receiving data from and/or relating to the connected equipment 610. The data can include timeseries values for monitored variables. The data can also include status information such as status codes indicating normal operation, on/off status, fault conditions, etc. The fault prediction model 808 can stream such data continuously from the connected equipment 610 or receive batches of such data, for example.

The fault prediction model 808 is configured to predict a future fault based on the timeseries data relating to the connected equipment 610. The fault prediction model 808 can include a neural network or other artificial intelligence model trained to predict future faults. The fault prediction model 808 can work as a classifier to classify sets of timeseries data relating to the connected equipment 610 as corresponding to conditions that indicate different types of faults that will occur, in various scenarios. The fault prediction model 808 thereby outputs a predicted fault. The predicted fault output by the fault prediction model 808 can include a type of the fault, a predicted timing of the fault, a confidence in the fault prediction and/or other information relating to a future fault condition predicted to occur by the fault prediction model 808.

In some embodiments, the predicted fault from the fault prediction model 808 is communicated to the equipment operational change model 810. The equipment operational change model 810 is configured to determine an operational change for the equipment intended to and/or expected to prevent or mitigate the predicted fault. For example, changing an internal operating settings of the connected equipment 610 may help to mitigate the predicted fault (e.g., reduce consequences of the fault, reach a less severe fault condition, delay the fault condition, etc.) or prevent the predicted fault (e.g., enable continuation of normal operation).

The equipment operational change model 810 receive the monitored variables and/or status information from the connected equipment 610 and use such information in combination with the predicted fault to determine the operational change. The equipment operational change model 810 may be a neural network or other artificial intelligence model trained using an actual and/or synthetic set of timeseries data showing results of different operational changes with respect to preventing or mitigating fault conditions (e.g., trained by training engine 818). As another example, the equipment operational change model 810 can include a rules-based approach whereby predefined rules are executed to determine the operational change based on the predicted fault. As one such example, the predefined rules may indicate that a certain setpoint should be adjusted in one direction by a certain amount in response to prediction of a particular type of fault. Various such examples are possible and enable the equipment operational change model 810 to output an equipment operational change to the connected equipment controller 802 as shown in FIG. 8 . In response to the equipment operational change from the fault management system 502, the connected equipment controller 802 operates the connected equipment 610 to automatically implement the equipment operational change as an automated action. The fault management system 502 thereby alters operation of the connected equipment 610 to prevent or mitigate the predicted fault.

In some embodiments, the predicted fault from the fault prediction model 808 is communicated to the building operational change model 810. The building operational change model 812 is configured to determine a building operational change intended to and/or expected to prevent or mitigate the predicted fault. The building operational changes are changes to be implemented using one or more building devices other than the connected equipment 610 of relevance in the predicted fault. For example, a building operational change can include changing a load on the connected equipment 610 (e.g., increasing or decreasing demand for a resource generated by the connected equipment 619 by changing other building setpoints), time-shifting operations of the connected equipment 610, changing environmental conditions around the connected equipment 610, changing characteristics of an input resource to the connected equipment 610, etc.

The building operational change model 812 may receive various building data, including in some examples the monitored variables and status information from the connected equipment 610, and use such information in combination with the predicted fault to determine a building operational change to prevent or mitigate the predicted fault. The building operational change model 812 may be a neural network or other artificial intelligence model trained using an actual and/or synthetic set of timeseries data showing results of different operational changes with respect to preventing or mitigating fault conditions (e.g., trained by training engine 818). As another example, the building operational change model 812 can include a rules-based approach whereby predefined rules are executed to determine the operational change based on the predicted fault. As one such example, the predefined rules may indicate that a certain building setpoint should be adjusted in one direction by a certain amount in response to prediction of a particular type of fault. Various such examples are possible and enable the building operational change model 812 to output an equipment operational change to the building controller 808 as shown in FIG. 8 . In response to the building operational change from the fault management system 502, the building controller 802 operates the building 10 (e.g., one or more building devices in building 10) to automatically implement the building operational change as an automated action. The fault management system 502 thereby alters operation of the building 10 to prevent or mitigate the predicted fault of the connected equipment 610.

In some embodiments, the predicted fault from the fault prediction model 808 is provided to the maintenance model 814. The maintenance model 814 is configured to determine a maintenance schedule intended to and/or expected to prevent or mitigate the predicted fault, for example in an optimal manner. The maintenance schedule can define one or more maintenance actions to be taken at one or more future times, for example by one or more service technicians. The maintenance actions can include maintenance on the connected equipment 610 and/or on other elements of the building 10.

The maintenance model may receive various other data inputs, including monitored variables and status information from the connected equipment, service technician schedules, parts availability and lead time information, and/or maintenance budget information, etc. and use such information in combination with the predicted fault from the fault prediction model 808 to determine a maintenance schedule for the building 10.

The maintenance model 814 may be a neural network or other artificial intelligence model trained using an actual and/or synthetic set of timeseries data showing results of different maintenance actions with respect to preventing or mitigating fault conditions (e.g., trained by training engine 818). As another example, the maintenance model 814 can include a rules-based approach whereby predefined rules are executed to determine the operational change based on the predicted fault. As one such example, the predefined rules may indicate that a certain maintenance action should be performed before predicted occurrence of a particular type of fault to prevent the fault. Various such examples are possible and enable the maintenance model 814 output a maintenance schedule to the work order system 806 as shown in FIG. 8 . In response to the maintenance schedule from the fault management system 502, the work order system 806 causes the scheduled maintenance to be performed, for example by automatically generating a work order for the scheduled maintenance and transmitting such orders to technicians, automatically ordering required tools or parts for performing the scheduled maintenance, etc. The fault management system 502 thereby causes performance of maintenance actions to prevent or mitigate the predicted fault.

FIG. 8 shows the fault management system 502 as also including a root cause discovery tool 816. The root cause discovery tool 816 is shown as receiving the predicted fault from the fault prediction model 808 and as being in communication with the connected equipment 610. The root cause discovery tool 816 may perform various operations to diagnose the root cause of a predicted fault, occurring fault, or previous fault. In some examples, the root cause discovery tool 816 is configured to perform experiments by altering operation of the connected equipment 610 and/or other elements of the building 10 to generate information that can help indicate the root cause of a fault. The root cause discovery tool 816 may also be configured to determine whether an equipment operational change, a maintenance action, or a building operational change is most suitable to (e.g., most likely, most reliable, most efficient, etc.) preventing or mitigating a predicted fault, and coordinate operation of the various elements of the fault management system 502 accordingly (e.g., to cause implementation of the most suitable solution while causing omission of operation of other components). In various embodiments, one or more of the root cause discovery tool 816, maintenance model 814, building operational change model 812, and equipment operational change model 810 are omitted.

The fault management system 502 is also shown as including training engine 818. The training engine 818 can be adapted to train, tune, generate, update, adjust, etc. the fault prediction model 808, the equipment operational change model 810, the building operational change model 812, and/or the maintenance model 814 in various embodiments. The training engine 818 can implement supervised or unsupervised training approaches in various embodiments, for example using a generative adversarial network (GAN), including a conditional embedder generative adversarial network (CEGAN) as described below. The training engine 818 can access various data from and relating to the connected equipment 610 and the building 10 and use such data for development and adjustment of various elements of the fault management system 502 in various embodiments.

Automated Prediction Horizon

Referring now to FIGS. 9-16 , features relating to automatically selecting a prediction horizon for the fault prediction model 808 are shown, according to various embodiments. The prediction horizon is the amount of time ahead over which predictions are made by a model or algorithm. For example, an embodiment of the fault prediction model 808 that predicts whether a fault will occur up to one day after a current time has a prediction horizon of one day while an embodiment of the fault prediction model 808 that predicts whether a fault will occur up to two days after a current time has a prediction horizon of two days, etc.

Longer prediction horizons provide more time for actions (changes in equipment operation, maintenance, replacement, building usage, etc.) to prevent or mitigate the fault. However, accuracy, reliability, and other performance metrics may worsen as the prediction horizon lengthens, because it is generally more difficult to forecast further into the future. Selection of the prediction horizon is thus material to how well a model performs at fault prediction and how well a system may be able to intervene in response to fault predictions.

In some examples, the prediction horizon may be preset or defined generically (e.g., by a manufacturer or service provider) for all units of connected equipment, all building sites, etc. The prediction horizon could be manually selected by a user. However, model performance is dependent on various additional factors, for example the quality and size of training data sets for particular units of connected equipment, according to relationships that are not definable by analytic rules or readily assessable through manual review. In response to such challenges, features shown in FIGS. 9-16 and described with reference thereto provide for autonomous determination of an ideal prediction horizon for fault prediction models 808, i.e., for particular units of equipment and based on the available training data the corresponding equipment unit. The resulting models use prediction horizons that ideally balance prediction performance (accuracy, etc.) with the amount of time provided to respond to such predictions. The examples herein refer to fault predictions, with the teachings herein also applicable to predictions of other conditions, events, values, etc.

Referring now to FIG. 9 , a flowchart of a process 900 for selecting a prediction horizon for the fault prediction model 808 is shown, according to some embodiments. The process 900 can be executed by fault management system 502, for example by the training engine 818. The process 900 may be part of training the fault prediction model 808 which is then used for online fault predictions and for affecting equipment operational changes, building operation changes, or maintenance activities as described above. The following description makes reference to FIG. 10 and also the example scenarios shown in FIGS. 11-13 , with process 900 also capable of handling many other scenarios.

At step 902, process 900 is initialized by selecting an initial range, with n denoting the selected range in FIG. 9 and FIG. 10 . The initial range may run from a minimum possible prediction horizon (e.g., zero) to a maximum prediction horizon (e.g., set by a user, sixteen days in various examples here such that n=16, etc.), such that the process 900 is initialized with the full range of possible prediction horizons from which process 900 can select. For example, FIGS. 11-13 show scenarios where the initial range runs from zero days to sixteen days. Process 900 can also include setting a resolution of the range, i.e., the smallest unit of time used in process 900. In the example of FIGS. 11-13 , a one-day resolution is selected. Any other resolution (e.g., one-hour resolution, two-hour resolution, half-day resolution, two-day resolution, etc.) can be used in other embodiments. Using discrete intervals (integer days) in process 900 can reduce computational complexity relative to a process which selects along a continuous timeline, for example.

At step 904, a midpoint of the range n is selected as the horizon point. The midpoint may be an exact middle of the range, i.e., n/2, if possible given the length of n and the selected resolution, or may be selected as the closest point above or below the middle of the range. FIG. 10 illustrates a branch diagram starting from a first node 1002 representing the midpoint n/2 selected at step 904. In the examples of FIGS. 11-13 , an example initial range is sixteen hours with one-hour resolution, with a first midpoint 1102 selected at hour eight.

At step 906, a prediction model is generated for the horizon point, i.e., for a prediction horizon having the value selected in step 904. In the examples of FIGS. 11-13 and for a first instance of step 906, a prediction model is generated having a prediction horizon of eight hours. Generating the prediction model can include labeling or sequencing a set of training data based on the prediction horizon and using such training data in a machine learning process to train a fault prediction model that predicts faults ahead in time by the selected prediction horizon (by the amount indicated by the horizon point), for example as shown in FIG. 14 and described with reference thereto below.

At step 908, an evaluation is performed of the model generated in step 906 and a decision is made as to whether the evaluation was successful or unsuccessful (e.g., whether a performance criteria is satisfied). The evaluation may be performed as described below with reference to FIGS. 14-15 in some embodiments. For example, the evaluation may involve determining if model predictions would be acceptably accurate if the selected horizon point is used as the prediction horizon and given the available training data in a particular scenario. A result of the evaluation may indicate one or more values of one or more performance metrics for a model which uses the selected horizon point and/or indications of whether the one or more values exceed one or more corresponding thresholds. A determination can thus be made in step 908 as to whether the model using the selected horizon point successfully passes an evaluation or fails the evaluation.

If model evaluation is successful (i.e., the model passes the evaluation, “yes” from step 908), process 900 proceeds to step 910. Moving to step 910 indicates that the model is sufficiently accurate or satisfies other evaluation criteria when the tested horizon point selected in step 904 is used as the model's prediction horizon. This indicates that the tested horizon point is less than or equal to the ideal horizon point. However, it does not necessarily indicate that the tested horizon point is exactly equal to the ideal horizon point because it is possible that longer prediction horizons could also satisfy the model evaluation criteria.

At step 910, a determination is made as to whether the horizon point is a leaf node, i.e., a smallest or final division given the resolution used by process 900 such that no further divisions can be made. For example, in the example of FIG. 10 , the illustration 1000 shows a tree diagram stemming from an initial node 1002 (a first level, denoted as n/2), which branches left and right to a second level 1004 with two nodes (at n/4 and 3n/4), which then branch further to a third level 1006 with four nodes (at n/8, 3n/8, 5n/8, 7n/8), which then branches even further to fourth level 1008 with eight nodes (at n/16, 3n/16, 5n/16, 7n/16, 9n/16, 11n/16, 13n/16, 15n/16). The nodes of the fourth level 1008 are the end of branches of the tree diagram 1000, and are thus considered leaf nodes. In this example, step 910 includes determining whether the selected horizon point is at the fourth level 1008 (which would be reached through multiple iterations of steps of process 900), or whether another level (i.e., additional branching) is still available. For example, in FIG. 10 , n/2 is not a leaf node, corresponding to “no” at step 910, while any of n/16, 3n/16, 5n/16, 7n/16, 9n/16, 11n/16, 13n/16, 15n/16 are leaf nodes, corresponding to “yes” at step 910.

If the horizon point is not a leaf node (“no” in step 910), process 900 proceeds to step 912 in which the range n is divided into two partitions. The two partitions are designated the “left partition” which begins at the beginning of the range n and ends at the horizon point selected in step 904 and the “right partition” which begins at the horizon point selected in step 904 and ends at the end of the range n. Step 912 includes selecting the right partition and updating the range n to be equal to the right partition (i.e., the second half of the previous range n). The midpoint of the newly selected range n is then assigned as the horizon point at step 904. For example, the new horizon point would be selected in steps 912 and 904 by moving to a right branch in the diagram of FIG. 10 (e.g., from n/2 to 3n/4; from n/4 to 3n/8, etc.). The horizon point is thus adjusted to a midpoint of the segment between the prior horizon point and to the end (maximum) of the segment for which the horizon point is the midpoint. The horizon point is thus adjusted to values at midpoints of successively narrower periods, with the next period greater than the horizon point if selected at step 912.

As one example, FIG. 13 shows an example where the evaluation of a first horizon point 1102 (hour eight) is successful in step 908 and the first horizon point 1102 is not a leaf node in step 910, such that a right partition (hour nine through hour sixteen) is selected in step 912 and a new horizon point (second point 1304, hour twelve) is selected in step 904. It should be understood that, in various embodiments, end points of ranges can be included or excluded when selecting partitions, ranges, and midpoints in execution of process 900, as may be apparent from the variety of examples shown herein.

The new horizon point selected in steps 912 and 904 is then used in step 906 to generate a new model for the new horizon point (or otherwise adapted the model to use the new horizon point) which is evaluated as discussed herein at step 908. If model evaluation is successful, step 908 returns to step 910, where process 900 again checks whether the horizon point is a leaf node. In some scenarios, process 900 iterates through steps 904, 906, 908, 910, and 912 (and, in some cases, steps 916 and 918 described below) until reaching step 910 in an iteration where the horizon point is a leaf node (i.e., “yes” at step 910). In response to a “yes” at step 910 (i.e., model evaluation is successful for a leaf node), that horizon point is used as the prediction for online control.

FIG. 13 shows one such example. In the example of FIG. 13 , the evaluation of a first horizon point 1102 (hour eight) is successful in step 908 and the first horizon point 1102 is not a leaf node in step 910, such that a right partition (hour nine through hour 16) is selected in step 912 and a new horizon point (second point 1304, hour twelve) is selected in step 904. Then, in a second iteration, the evaluation of the second horizon point 1304 is successful in step 908 and the second horizon point 1304 is not a leaf node, such that a right partition (hour thirteen through hours sixteen) is selected in step 912 and a new horizon point (third horizon point 1306, hour fifteen) is selected in step 904. In a third iteration, the evaluation of the third horizon point 1306 is successful in step 908 and the third horizon point 1306 is not a leaf node, such that a right partition (hour sixteen) is selected in step 912 and the remaining hour is used as the new horizon point (fourth horizon point 1308, hour sixteen). In the example of FIG. 13 , the evaluation is successful at step 908 for the fourth horizon point 1308, and the fourth horizon point 1308 is a leaf node (“yes” at step 910), so the fourth horizon point 1308 (i.e., sixteen hours) is used as the prediction horizon at step 914.

If a model evaluation at step 908 is unsuccessful (e.g., the model is not sufficiently accurate), process 900 proceeds to step 916. Moving to step 916 indicates that the model is not sufficiently accurate or fails to meet other evaluation criteria when the tested horizon point selected in step 904 is used as the model's prediction horizon. This indicates that the tested horizon point is greater than the ideal horizon point and should be set to a lower value to improve model performance. Step 916 checks whether the horizon point (i.e., as used in the unsuccessful evaluation) is a leaf node. Step 916 can be substantially the same as step 910 described above.

If the horizon point is not a leaf node (i.e., “No” at step 916), process 900 proceeds to step 918 where the left partition is taken, in particular the period between the horizon point and the beginning (minimum) of the period for which the horizon point is the midpoint. Step 918 can be characterized as taking the opposite action as in step 912. That is, Step 918 includes selected the left partition and updating the range n to be equal to the left partition (i.e., the first half of the previous range n). For example, in the new horizon point would be selected in steps 918 and 904 by moving to a left branch in the diagram of FIG. 10 (e.g., from n/2 to n/4; from 3n/4 to 5n/8, etc.). The horizon point is thus adjusted to a midpoint of the segment between the prior horizon point and to the beginning (minimum) of the segment for which the horizon point is the midpoint. The horizon point is thus adjusted to values at midpoints of successively narrower periods, with the next period less than the horizon point if selected at step 912. The process 900 thus loops through steps 904, 906, 908, 916, and 918 while advancing to a lower (shorter) horizon in response to an unsuccessful evaluation.

As one example, FIG. 12 shows an example where the evaluation of a first horizon point 1102 (hour eight) is unsuccessful (fails) in step 908 and the first horizon point 1102 is not a leaf node in step 916, such that a left partition (hour 1 through hour 7) is selected in step 912 and a new horizon point 1204 (second point 1204, hour 4) is selected in step 904. FIG. 12 also shows similar partitioning following failure of a subsequent evaluation of a model using the second horizon point and following failure of an evaluation of a model using a third horizon point 1206. In the example of FIG. 12 , evaluation is successful for a fourth horizon point 1208 which is a leaf node and is thus used as the horizon point in a model for online use via step 914.

Various leaf nodes can be selected as the horizon points as outputs of the process via step 914 in scenarios where the model evaluation for a leaf node at step 908 is successful. FIGS. 11-13 all show such examples. The scenarios of FIGS. 12 and 13 are described above. In FIG. 11 , evaluation fails on a first iteration of step 908, so the second horizon point 1204 is selected for a next iteration as in the example of FIG. 12 . The example of FIG. 11 then diverges from the example of FIG. 12 because the evaluation is successful for a model using the second horizon point 1204 (e.g., due to different training data in the scenarios, due to different criteria used in the evaluation). In the example of FIG. 11 , in response to the successful evaluation, a right partition is taken from the second horizon point 1204 and a third horizon point 1106 (hour six) is used. Then, in a next iteration, the evaluation is successful for the third horizon point 1106 so a right partition is taken to a fourth horizon point 1108 (hour seven), which is a leaf node. A final evaluation is successful for the fourth horizon point 1108, and because it is a leaf node it is then used as the horizon point for a model used online (e.g., a fault prediction model used as in FIG. 8 ).

In other scenarios, the model evaluation at step 908 will be unsuccessful for a leaf node, such that process 900 reaches step 920. Because model evaluation is unsuccessful, that point will not be used as the prediction horizon for online control. Instead, in step 920, the most recent (i.e., from the order of multiple iterations of step 904) horizon point with a successful evaluation is selected for uses as the online prediction horizon. Step 920 can include tracing back up a graph or tree as in FIG. 10 until a successful evaluation is found. If no evaluations were successful, zero is the output of process 900 and becomes the prediction horizon. If zero is determined as the prediction horizon, a smaller resolution (e.g., hours instead of days, minutes instead of hours) can be used to find a horizon over which predictions can be made).

As one example, with reference to FIG. 10 , if a model evaluation is unsuccessful at leaf node 13n/16, step 920 may then check the evaluation up the branch at previous node 7n/8. In this example, the evaluation was unsuccessful at node 7n/8 (i.e., in order to reach node 13n/16), so step 920 would look back another iteration to find that the evaluation was successful for node 3n/4. The value at node 3n/4 would be the prediction horizon determined in step 920 as the output of process 900.

Process 900 thereby operates to find the longest horizon for which a model evaluation is successful, while minimizing the number of evaluations that need to be performed. For example, other implementations may check all options (e.g., 16 options in the examples of FIGS. 11-13 ) and create models and perform evaluations for all such options for the prediction horizon. In contrast, process 900 finds a solution from the same number of options with only four evaluations performed. Process 900 is therefore significantly more efficient and requires less memory and computing resources as compared to other possible implementations.

Referring now to FIG. 14 , a diagram of a process 1400 for generating performance metrics in a model evaluation based on a selected horizon point to be evaluated is shown, according to some embodiments. Process 1400 can be executed as part of step 906 and/or step 908 of FIG. 9 , for example.

As illustrated in FIG. 14 , training data (block 1402) is provided as an input to a step of labeling the data with fault information (block 1404). Block 1404 also receives the horizon point to be evaluated (block 1402) which may be selected by an iteration of step 904 of FIG. 9 , for example. Labelling the data with fault information in block 1404 can include sequencing the data based on the horizon point (i.e., based on the selected prediction horizon). For example, given a prediction horizon of length l and a historical fault in the training data at time T (e.g., as indicated by status codes in the training data), data at (or for some period up to) time T−l may be labeled in step 1400 as being associated with the fault at time T. Such labeling encodes the prediction horizon in the training data, such that the labelled training data includes a representation of the predictive relationships to be explored during model training.

The labelled fault information 1404 is then provided to prediction model training (block 1408). The labelled fault information 1404 can be used in a machine learning approach, for example a supervised or unsupervised machine learning approach to train the prediction model. At least in part due to the labelling of the training data based on the horizon point to be evaluated, block 1408 a model is trained to predict faults by an amount of time ahead indicated by the horizon point. A prediction model (block 1410) that uses the prediction horizon indicated by block 1406 is thus output from block 1408.

The prediction model (block 1410) is then used to generate test data (block 1412). For example, the prediction model may be used in a simulation and/or applied to a set of validation data. Test data can thus be generated that includes, for example, predictions made by the prediction model and actual faults which occurred in the validation data and/or simulation. Such test data can then be processed through various analytics, formulas, algorithms, etc. to generate one or more performance metrics (block 1414) for the prediction model. FIG. 15 shows various performance metrics that can be used and further steps for using performance metrics provided at block 1414.

Referring now to FIG. 15 , a block diagram of a process 1500 for evaluating performance metrics of a model is shown, according to some embodiments. Process 1500 can be performed with or after (e.g., in response to) block 1408 of process 1400, and may be included as part of step 908 of process 900, for example.

FIG. 15 illustrates a process 1500 that includes calculating performance metrics 1502, which can include determining a variety of metrics as shown in list 1504 including precision, recall, false positive rate, true positive rate, area under a receiver operating characteristic curve (ROC AUC), and accuracy. Such metrics can be calculated using test data from process 1400, for example.

At decision block 1506, a determination is made as to whether the values of one or more of the various possible metrics exceed one or more thresholds. For example, block 1506 can include comparing values of multiple metrics to multiple, corresponding thresholds. As another example, the metrics can be normalized and, in some embodiments, combined (e.g., averaged) for comparison to a common threshold. Block 1506 uses comparison of the one or metrics to one or more thresholds to determine whether model evaluation is successful (“yes,” block 1510) or a failure (“no,” block 1508). In some embodiments, an evaluation fails if any of multiple metrics does not exceed a thresholds, such that all thresholds must be exceed for the evaluation to be successful. In other embodiments, an evaluation is successful if any one metric exceeds a thresholds. In yet other embodiments, an evaluation is successful if a certain number or fraction (e.g., half, ¾, etc.) of the metrics exceed corresponding thresholds. In any case, block 1506 determines whether the evaluation is considered to be successful or unsuccessful, with such a determination being an output of process 1500. The determination of whether the evaluation is successful or unsuccessful can then be used in step 908 of process 900 as described above.

Referring now to FIG. 16 , a flowchart of a process 1600 for multi-tiered prediction horizon determination is shown, according to some embodiments. Process 1600 can be executed by the training engine 818, for example, and can include multiple executions of process 900 as detailed below.

At step 1602, process 900 is executed at a resolution of one-day to select a day horizon. That is, process 900 operates with a smallest increment of one day, such that each node corresponds to a number of days ahead for uses in defining the prediction horizon (e.g., one day, two days, etc. through sixteen days). Process 900 can be executed substantially as described above, and outputs a selected day from step 1602.

At step 1604, process 900 is run again, but at a smaller resolution (e.g., one-hour resolution) and limited within the day selected in step 1602. In step 1604, an hour within the selected day is thereby determined in order to set the prediction horizon as a number of days (from step 1602) plus a number hours (from step 1604). At step 1606, this day-hour prediction horizon is used for online fault prediction, for example by the fault prediction model 818 of FIG. 8 .

Process 1600 thereby provides an efficient process for selecting a prediction horizon at a high resolution (e.g., an hourly resolution) given a significantly larger initial set of options. For example, if a maximum period considered is 16 days, 16 days times 24 hours leaves 384 possible periods that would need to be evaluated in some implementations. However, the efficient, staged approach narrows to a selected day and hour in eight or fewer iterations of process 900.

Although process 1600 and other embodiments herein and described with reference to single days and single hours, various periods and subperiods can be used in various embodiments. For example, groups of two days, three days, non-integer numbers of days, weeks, months, etc. can be selected between in some examples, as can shorter periods (e.g., fifteen minutes, half hours, two hours, four hours, six hours, half days, etc.) in various embodiments. Any divisions, periods, segments, resolutions, etc. can be used in various embodiments as may be suitable for particular applications, for example for different types of equipment, types of faults, types of facilities, or other considerations.

CONFIGURATION OF EXEMPLARY EMBODIMENTS

The construction and arrangement of the systems and methods as shown in the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.). For example, the position of elements can be reversed or otherwise varied and the nature or number of discrete elements or positions can be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present disclosure. The order or sequence of any process or method steps can be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes, and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present disclosure.

The present disclosure contemplates methods, systems and program products on any machine-readable media for accomplishing various operations. The embodiments of the present disclosure can be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

Although the figures show a specific order of method steps, the order of the steps may differ from what is depicted. Also two or more steps can be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps. 

What is claimed is:
 1. A method for building equipment, the method comprising: automatically selecting a prediction horizon used by a predictive model for the building equipment by performing evaluations of model performance at successively narrower ranges of possible prediction horizons until the prediction horizon is determined based on results of the evaluations; and using the predictive model with the prediction horizon to perform an automated control action comprising at least one of controlling or monitoring the building equipment; wherein the building equipment operates to affect a physical condition of one or more buildings.
 2. The method of claim 1, wherein using the predictive model comprises performing fault predictions, the method further comprising automatically affecting an operation of the building equipment based on whether a fault of the building equipment is predicted to occur within the prediction horizon using the predictive model.
 3. The method of claim 1, further comprising choosing the successively narrower ranges by choosing higher ranges in response to successful results of the evaluations and choosing lower ranges in response to unsuccessful results of the evaluations.
 4. The method of claim 1, further comprising choosing the successively narrower ranges by: dividing an initial range at a midpoint of the initial range; choosing a first narrower range of the successively narrower ranges as a portion of the initial range greater than the midpoint in response to a successful evaluation result based on the midpoint of the initial range; and choosing the first narrower range of the successively narrower ranges as a portion of the initial range less than the midpoint in response to an unsuccessful evaluation result based on the midpoint of the initial range.
 5. The method of claim 4, further comprising: dividing the first narrower range at the midpoint of the first narrower range; choosing a second narrower range of the successively narrower ranges as a portion of the first narrower range greater than the midpoint in response to a successful evaluation result based on the midpoint of the first narrower range; and choosing the second narrower range of the successively narrower ranges as a portion of the first narrower range less than the midpoint in response to an unsuccessful evaluation result based on the midpoint of the first narrower range.
 6. The method of claim 5, further comprising: dividing the second narrower range at the midpoint of the second narrower range choosing a first end point greater than the midpoint in response to a successful evaluation result based on the midpoint of the first narrower range; and choosing a second end point less than the midpoint in response to an unsuccessful evaluation result based on the midpoint of the first narrower range.
 7. The method of claim 6, further comprising using the first end point or the second end point as the prediction horizon in response to a successful evaluation result using the first end point or the second end point as the prediction horizon.
 8. The method of claim 1, wherein the evaluations comprise comparing a plurality of performance metrics to a plurality of thresholds.
 9. The method of claim 8, wherein the plurality of performance metrics comprise two or more of a precision metric, a recall metric, a false positive rate, a true positive rate, an accuracy metric, and an area under a receiver operating characteristic curve.
 10. The method of claim 1, wherein performing the evaluations of model performance at the midpoints comprises: using the midpoints as the prediction horizons for fault prediction models; training the fault prediction models; and executing tests of the fault prediction models.
 11. A building system, comprising: building equipment operable to affect a condition of a building; and circuitry programmed to: automatically select a prediction horizon for a predictive model by performing evaluations of model performance at successively narrower ranges of possible prediction horizons until the prediction horizon is determined based on results of the evaluations; and using the predictive model with the prediction horizon to perform an automated control action comprising at least one of controlling or monitoring the building equipment.
 12. The system of claim 11, wherein: the circuitry comprises a first portion locally integrated with the building equipment and a second portion at a cloud system; the second portion automatically selects the prediction horizon, trains a machine learning model based on the prediction horizon, modifies the machine learning model to create a modified machine learning model suitable for edge execution, and provides the modified machine learning model to the first portion; and the first portion uses the modified machine learning model to predict whether a fault of the building equipment will occur over the prediction horizon.
 13. The system of claim 11, wherein using the predictive model comprises performing fault predictions for the building equipment, and wherein the circuitry is programmed to perform the automated control action by automatically influencing operation of the building equipment based on whether a fault is predicted to occur at the prediction horizon.
 14. The system of claim 11, wherein the circuitry is further programmed to choose the successively narrower ranges by choosing higher ranges in response to successful results of the evaluations and choosing lower ranges in response to unsuccessful results of the evaluations.
 15. The system of claim 11, wherein the circuitry is further programmed to choose the successively narrower ranges by: dividing an initial range at a midpoint of the initial range; choosing a first narrower range of the successively narrower ranges as a portion of the initial range greater than the midpoint in response to a successful evaluation result based on the midpoint of the initial range; choosing the first narrower range of the successively narrower ranges as a portion of the initial range less than the midpoint in response to an unsuccessful evaluation result based on the midpoint of the initial range; dividing the first narrower range at the midpoint of the first narrower range; choosing a second narrower range of the successively narrower ranges as a portion of the first narrower range greater than the midpoint in response to a successful evaluation result based on the midpoint of the first narrower range; choosing the second narrower range of the successively narrower ranges as a portion of the first narrower range less than the midpoint in response to an unsuccessful evaluation result based on the midpoint of the first narrower range; dividing the second narrower range at the midpoint of the second narrower range choosing a first end point greater than the midpoint in response to a successful evaluation result based on the midpoint of the first narrower range; choosing a second end point less than the midpoint in response to an unsuccessful evaluation result based on the midpoint of the first narrower range; and using the first end point or the second end point as the prediction horizon in response to a successful evaluation result using the first end point or the second end point as the prediction horizon.
 16. The system of claim 11, wherein the evaluations comprise comparisons of a plurality of performance metrics to a plurality of thresholds.
 17. The system of claim 16, wherein the plurality of performance metrics comprise two or more of a precision metric, a recall metric, a false positive rate, a true positive rate, and accuracy metric, and an area under a receiver operating characteristic curve.
 18. One or more non-transitory computer-readable media storing instructions that, when executed by one or more processors, perform operations comprising: automatically selecting a prediction horizon by performing evaluations of model performance for successively narrower ranges of possible prediction horizons until the prediction horizon is determined based on results of the evaluations; and using the predictive model with the prediction horizon to perform an automated control action for building equipment.
 19. The one or more non-transitory computer readable media of claim 18, wherein the operations further comprise choosing the successively narrower ranges by choosing higher values in response to successful results of the evaluations and choosing lower values in response to unsuccessful results of the evaluations.
 20. The one or more non-transitory computer readable media of claim 18, wherein the evaluations comprise comparisons of a plurality of performance metrics to a plurality of thresholds, wherein the plurality of performance metrics comprise two or more of a precision metric, a recall metric, a false positive rate, a true positive rate, and accuracy metric, and an area under a receiver operating characteristic curve. 